Arrangement at feeding tree trunks for trimming by shearing

ABSTRACT

Device for feeding tree trunks for delimbing including a set of feed rollers, a constant speed drive motor, and a torque converter interposed between the motor and the feed rollers.

United States Patent Inventor Karl Thore Llndblom Alfta, Sweden Appl. No. 864,808 Filed Oct. 8, 1969 Patented Nov. 9, 1971 Assignee Ostbergs Fabrik AB Allta, Sweden Priority Oct. 10, 1968 Sweden 13668/68 ARRANGEMENT AT FEEDING TREE TRUNKS FOR TRIMMING BY SHEARING 2 Claims, 1 Drawing Fig.

US. Cl. 144/2 Z, 143/84 F Int. Cl. A0lg 23/02 Field 01 Search 144/2 2,

246 R, 246 A-246 G; 143/84 R, 84 F, 84 H, 32

[56] References Cited UNITED STATES PATENTS 2,764,870 10/1956 Slomer 143/32 2,794,466 6/1957 Leffler..... 144/246 G 2,817,375 12/1957 Traben 143/84 F 2,961,017 11/1960 Traben.... 143/84R 2,989,095 6/1961 Thunell 143/84 R 3,326,251 6/1967 Herolf et a1 144/2 2 Primary Examiner-Gerald A. Dost Attorney-Pierce, Scheffler and Parker ABSTRACT: Device for feeding tree trunks for delimbing including a set of feed rollers, a constant speed drive motor. and a torque converter interposed between the motor and the feed rollers.

PATENTEU Nov 9.911 3,618,645

ARRANGEMENT AT FEEDING TREE TRUNKS FOR TRIMMING BY SHEARING This invention relates to an arrangement for use at the feeding of tree trunks for trimming by shearing, in which a motor is in driving connection with trunk feed means, such as feed rolls, for driving the trunk in question into engagement with shear knives.

In order to shorten the relatively long time required by the trimming of felled trees as a part of the total working cyclus, ih many cases the rapid shearing method is applied, in which the trunk is caused to pass a set of usually stationary shear knives. In said cases the feed means for advancing the trunk have been dimensioned with respect to the greatest branch dimensions possibly occurring, in order not to jeopardize the shearing operation. Consequently, the feed means heretofore used have been extremely expensive, bulky and heavy in relation to the obviously very low utilization of the effect available.

This disadvantage is eliminated in that between the motor and the trunk feed means is placed a torque converter known per se, the gear ratio of which varies in inverse proportion to the shear resistance mediated to the trunk feed means, and thereby the shear force increases in proportion to the shear resistance.

The invention is described in greater detail in the following, with reference to the accompanying drawing in which the only FIGURE in a schematic way shows the arrangement according to the invention.

The reference number 1 designates a tree trunk in cross section which for being driven against a set of shear knives (not shown) is inserted between an upper and a lower feed roll 2 and 3, respectively, whereof the upper roll acts as a guide roll and the lower roll is driven by a shaft 4. Heretofore, the shaft 4 or corresponding means have been driven by the motor 5 with a substantially constant number of revolutions and constant torque, and therefore the motor has been dimensioned so as to ensure the cutting even of the thickest branches at the relatively high number of revolutions-or, more correctly, high trunk-feed speed-which is required for holding the trimming time within reasonable limits.

According to the invention, a conventional transmission unit 6 is placed between the shaft 4 of the feed roll 3 and the motor shafi 7. Said unit is constructed so as to bring about between the shafts 7 and 4 a gear ratio which automatically varies in inverse proportion to the torque acting on shaft 4 and thereby to the shear resistance produced by the branches of trunk l at the trimming operation. This condition is met by the so-called torque converter, the characteristics of which-to the present case-bring about a drive force acting upon the trunk which exponentially decreases with increasing trunk speed and vice versa. In other words, the thickest branches will be shom off slowly but with a very strong force, and the thinner branches and limbs will be shom off quickly by using a small force. Under any circumstances the capacity of the motor is utilized to its full extent, because the torque converter automatically adjusts at optimum the torque and number of revolutions to the trimming conditions as they prevail in the moment in question. Owing to the exponential characteristics of the torque converter, thus, the motor can be dimensioned for a remarkably low-rated output, which renders possible considerable savings in costs, weight and space, even with consideration paid to the torque converter to be added.

What I claim is:

1. In an apparatus for feeding a tree trunk for delimbing by pulling a tree trunk, with its root end first, through a set of shearing knives encircling such trunk, the combination of (1) a relatively low-effect drive motor having an output shaft, (2) a torque converter having its output torque varying in an inverse relationship to its output speed when subjected to a substantially constant input torque, and (3) rotational feed means having an input shaft, said torque converter being connected between the output shaft of the drive motor and the input shaft of the feed means, whereby the effective drive force acting on the feed means increases momentarily and the speed decreases correspondingly at the occurrence of thicker branches and vice versa at the occurrence of thinner branches and tree trunk portions substantially free from branches.

2. Apparatus according to claim 1, wherein said feed means is one roller in a pair of parallel feed rollers between which such tree trunk is engaged. 

1. In an apparatus for feeding a tree trunk for delimbing by pulling a tree trunk, with its root end first, through a set of shearing knives encircling such trunk, the combination of (1) a relatively low-effect drive motor having an output shaft, (2) a torque converter having its output torque varying in an inverse relationship to its output speed when subjected to a substantially constant input torque, and (3) rotational feed means having an input shaft, said torque converter being connected between the output shaft of the drive motor and the input shaft of the feed means, whereby the effective drive force acting on the feed means increases momentarily and the speed decreases correspondingly at the occurrence of thicker branches and vice versa at the occurrence of thinner branches and tree trunk portions substantially free from branches.
 2. Apparatus according to claim 1, wherein said feed means is one roller in a pair of parallel feed rollers between which such tree trunk is engaged. 